scholarly journals Compression strength perpendicular to grain of Serbian spruce (Picea omorika (Pancic) purkyně) wood from plantations and natural stands

2017 ◽  
pp. 171-188
Author(s):  
Danijela Petrovic ◽  
Zdravko Popovic ◽  
Nebojsa Todorovic
Keyword(s):  
Mechanical Properties ◽  
Regression Analysis ◽  
Tangential Direction ◽  
Annual Rings ◽  
Spruce Wood ◽  
Limit Strength ◽  
Picea Omorika ◽  
Natural Stands ◽  
Serbian Spruce ◽  
Conditional Limit

This paper presents the results of testing the compression of Serbian spruce wood from plantations and natural stands. Compression perpendicular to grain in radial and tangential direction was tested. A dilatation of 1% was taken for a conditional boundary dilatation, and the appropriate strength for the conditional limit strength was taken. Six trees from plantations and nine trees from natural stands were analyzed. In total, 309 samples were tested. The regression analysis examined the dependence of these mechanical properties on the width of the annual rings, the percentage of late wood and wood density.

scholarly journals Anisotropy of transversal swelling of Serbian spruce wood (Picea omorika (Pancic) Purkyně)

2018 ◽  
pp. 119-136
Author(s):  
Danijela Petrovic ◽  
Zdravko Popovic ◽  
Nebojsa Todorovic ◽  
Vojislav Dukic
Keyword(s):  
Regression Analysis ◽  
Growth Rings ◽  
Spruce Wood ◽  
Late Wood ◽  
Picea Omorika ◽  
Natural Stands ◽  
Serbian Spruce

The paper presents the results of analysis of anisotropy of transverse swelling of the Serbian spruce wood. The analysis included six trees that come from plantations and nine trees from natural stands of Serbian spruce, and a total of 3098 samples were tested. The results show a change in transversal anisotropy at the height of the tree, as well as its change in radius. The dependence of this property on the growth rings width, the participation of late wood and the density of wood was determined by regression analysis.

scholarly journals MOR and MOE of Serbian Spruce (Picea omorika Pančić/Purkyně) Wood from Natural Stands

2021 ◽  
Vol 72 (2) ◽  
pp. 193-200
Author(s):  
Danijela Petrović ◽  
Vojislav Dukić Dukić ◽  
Zdravko Popović ◽  
Nebojša Todorović
Keyword(s):  
Modulus Of Elasticity ◽  
Ring Width ◽  
Modulus Of Rupture ◽  
Bending Stress ◽  
Annual Ring Width ◽  
Spruce Wood ◽  
Picea Omorika ◽  
Natural Stands ◽  
Serbian Spruce ◽  
Proportionality Limit

The paper presents the results of testing the bending stress of Serbian spruce wood from natural stands. In testing the samples, in addition to the modulus of rupture, the bending stress at the proportionality limit, the ratio between the stress at the proportionality limit and the modulus of rupture as well as the modulus of elasticity of wood were determined. The study included nine trees from natural stands, and a total of 261 samples were tested. Regression analysis determined the dependences of these mechanical properties on the annual ring width, the proportion of late wood and wood density, as well as the dependence of the modulus of elasticity on the modulus of rupture.

Intra-Ring Variations in the Rolling Shear Modulus of Spruce Wood

Holzforschung ◽  
2001 ◽  
Vol 55 (5) ◽  
pp. 549-553 ◽  
Author(s):  
Jean-François Dumail ◽  
Lennart Salmén
Keyword(s):  
Mechanical Properties ◽  
Shear Modulus ◽  
Wall Structure ◽  
Annual Rings ◽  
Wood Material ◽  
Rolling Shear ◽  
Spruce Wood ◽  
Fiber Wall

Summary The mechanical properties of wood are highly related to its structure, and knowledge regarding the influence of, for instance, density and fiber wall structure is needed for a better utilisation of the wood material. In this work, the Iosipescu method was used to test wood in rolling shear in order to establish the intra-ring variations in the wet shear modulus of spruce wood. The shear modulus increased from the earlywood to the latewood within the annual rings. This increase in the wet shear modulus was explained to 80% by the variations in the density of the wood.

scholarly journals Variation in Mechanical Properties within Individual Annual Rings in the Resonance Spruce Wood (Picea abies (L.) Karst.)

2014 ◽  
Vol 65 (3) ◽  
pp. 215-223
Author(s):  
Waldemar Moliński ◽  
Edward Roszyk ◽  
Jakub Puszyński
Keyword(s):  
Mechanical Properties ◽  
Picea Abies ◽  
Annual Rings ◽  
Spruce Wood

scholarly journals Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

2021 ◽  
Vol 13 (10) ◽  
pp. 5494
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Tomáš Janda ◽  
Jan Sýkora ◽  
Pavel Padevět ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cross Section ◽  
Negative Impact ◽  
Tensile Tests ◽  
Thermal Recovery ◽  
Bending Test ◽  
Small Scale ◽  
Spruce Wood ◽  
The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

Mathematical Model of the Sintering Process of Iron-Copper Bearings

2007 ◽  
Vol 23 ◽  
pp. 119-122
Author(s):  
Cristina Teișanu ◽  
Stefan Gheorghe ◽  
Ion Ciupitu
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Mathematical Model ◽  
Regression Analysis ◽  
Function Optimization ◽  
Chemical Compositions ◽  
Sintering Process ◽  
Molybdenum Disulphide ◽  
Iron Copper ◽  
Antifriction Properties

The most important features of the self-lubricating bearings are the antifriction properties such as friction coefficient and wear resistence and some mechanical properties such as hardness, tensile strength and radial crushing strength. In order to improve these properties new antifriction materials based on iron-copper powders with several additional components (tin, lead and molybdenum disulphide) have been developed by PM techniques. To find the optimal relationship between chemical compositions, antifriction and mechanical properties, in this paper a mathematical model of the sintering process is developed, which highlighted the accordance of the model with data by regression analysis. For the statistical processing of the experimental data the VH5 hardness values of the studied materials were considered. The development of mathematical model includes the enunciation of the model, the establishment of the performance function (optimization) and the establishment of the model equations and verifying. The accordance of the model with experimental data has been highlighted by regression analysis

The effect of trace elements (Cu and Sn) on mechanical properties of steel castings

1980 ◽  
Vol 295 (1413) ◽  
pp. 125-125
Keyword(s):  
Mechanical Properties ◽  
Trace Elements ◽  
Regression Analysis ◽  
Experimental Work ◽  
High Strength Steel ◽  
Mechanical Performance ◽  
High Strength ◽  
Residual Elements ◽  
Steel Castings ◽  
Effect Of Copper

Because of the increase in the levels of residual elements in steel, a programme of work was initiated to determine the limits of copper and tin impurities that were tolerable in steel castings. A 1.5 % Mn—Mo steel was chosen as a base, since any effect of trace elements would be readily apparent in terms of mechanical performance in this medium—high strength steel. The effect of copper was investigated within the range < 0.01-0.5 %, and tin within the range < 0.01-0.26%. The results were analysed by using factorial analysis in the first instance and later, as the amount of experimental work expanded and more results became available, a regression analysis was used.

scholarly journals Regression analysis and statistical examination of Knoop Hardness on abrasion resistance in Lyca Beige Marbles

Filomat ◽  
2020 ◽  
Vol 34 (2) ◽  
pp. 609-614
Author(s):  
Burcu Aydin ◽  
Fusun Yalcin ◽  
Ozge Ozer ◽  
Gurhan Yalcin
Keyword(s):  
Mechanical Properties ◽  
Regression Analysis ◽  
Physical And Mechanical Properties ◽  
Production Method ◽  
Knoop Hardness ◽  
Decomposition Products ◽  
Marble Quarries ◽  
Selection Of

Marbles are secondary decomposition products formed by metamorphism of limestone. Effective classification of marble quarries in terms of quality enables the selection of a sustainable production method and safety application. This evaluation is based on physico-mechanical properties of the samples. Obtained results of physico-mechanical properties of the marbles were statistically analyzed using Stata 14 and SPSS 21 software. The marbles indicated mostly normal physical and mechanical properties. A strong inverse relationship exists between Abrasion Value and Knoop Hardness Determination that indicates a significant nonlinear relationship. Samples were distinguished into 3 groups of close similarity and related properties. The estimated value of the parameters is in the 95 % confidence interval. The equation obtained by regression analysis was used for the determination of resistance to abrasion.

scholarly journals Crown structure of Picea omorika trees in the plantation

2012 ◽  
Vol 64 (2) ◽  
pp. 605-611 ◽  
Author(s):  
M. Krstic ◽  
N. Stavretovic ◽  
V. Isajev ◽  
I. Bjelanovic
Keyword(s):  
Tree Height ◽  
Tree Crown ◽  
Crown Length ◽  
Crown Structure ◽  
Parabolic Function ◽  
Picea Omorika ◽  
Serbian Spruce ◽  
The Relationship ◽  
Total Tree ◽  
Stand Conditions

The study was carried out in Serbian spruce (Picea omorika Panc/Purkyn?) plantations in the western Serbia. The paper presents results of the analysis of crown development. The following elements were analyzed: total tree height, height of the crown base, absolute and relative crown length, maximal crown diameter, coefficient of crown spreading and degree of crown girth. We discuss approaches to the modeling of tree crown growth and development, growing under favorable environmental and stand conditions, without anomalies in development. In order to establish the relationship between analyzed factors, regression analyses were applied. Data fitting was by the analytic method, by the implementation of Prodan?s functions of growth, linear and parabolic function. Received models can be used for the simulation of various growth and developing processes in forest.

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